Modern gas turbines include a large number of small (less than 1 mm diameter) laser drilled holes to provide cooling in jet engine components. The majority of holes used for this purpose have been cylindrical. However, recently the benefits of using shaped holes have been recognized.

There are several reasons why laser drilling of shaped holes has become increasingly popular. First, shaped holes can provide superior cooling for a turbine engine component. Film cooling holes increase efficiency of cooling air by 30%, reducing the amount of air required for cooling. Proper design of cooling components with shaped holes can result in fewer holes to accomplish a superior result.

A second reason for the increasing popularity of shaped holes is that fewer holes mean shorter production cycle times, lower production costs, and a lower cooling air requirement. This results in a more efficient and cost effective engine.

The specific interest in laser processing comes from its speed relative to competitive methods and its ability to produce shaped holes in parts with thermal barrier coatings (TBC).

Work has been carried at Prima Power Laserdyne to develop laser and processing parameters to produce shaped holes with both coated and uncoated nickel based superalloys.

Drilling tests were carried out using ShapeSoft™, an S94P feature that supports drilling different shape holes. Some of the drilling results are highlighted in the pictures within this article.

ShapeSoft helps to create programs for producing cone, oblique cone, fan, racetrack and a variety of other shaped holes in a wide range of turbine engine components including blades, nozzle guide vanes and combustors for aero-engine and industrial gas turbine applications.

 

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